Glossary

SEALSee Reservoir. An impermeable fault or stratum of rock beneath or behind which hydrocarbons can accumulate.

SECONDARY POROSITYPorosity developed after the original deposition of a formation, for instance by the action of water on soluble components of the rock or well stimulation techniques.

SEISMIC ACQUISITION (2-D, 3-D, 4-D) Seismic data are used to map subsurface formations. A 2-D survey reveals a cross section of the subsurface. In a 3-D survey, seismic data are collected in the inline and crossline directions to create a three-dimensional image of the subsurface. In a 4-D or time-lapse 3-D survey, 3-D surveys are repeated over time to track fluid movement in the reservoir.

SEPARATORA process vessel used to separate gases and various liquids in a hydrocarbon stream. A Wellhead Separator is the first process vessel in a production operation, operating at or near wellhead pressures.

SET CASINGInstallation of steel pipe or casing in a well bore, normally cemented in place by surrounding it with a wall of cement.

SHOEThe strengthened fitting on the lower end of a string of casing to protect the tubulars and help direct the cement to the annulus.

SHOWEvidence of hydrocarbons in a formation such as fluorescence in cuttings or gas in the mud returning from down hole.

SHUT-IT PRESSUREThe pressure in a shut-in well; static pressure.

SIDE-TRACK/SIDE-TRACKED WELLA well re-drilled from an intermediate depth. Wells are re-directed or sidetracked for various reasons, but usually because of technical problems deeper in the original well.

SIDEWALL CORINGObtaining rock samples from the sides of a well bore using a special tool.

SOLUTION GASSee Associated Gas

SPACING The distance between wells producing from the same reservoir. Spacing is often expressed in terms of acres, e.g., 40-acre spacing, and is often established by regulatory agencies.

SPUDTo start drilling a new well (or re-start)

SQUEEZEInserting cement under pressure into the poorly sealed annulus of a well, past the existing material.

STAND OF PIPEA short length of drill pipe pre-assembled to save time in operations and stored vertically in the derrick ready for use, usually in lengths of three joints.

STEP-OUT WELL Well drilled adjacent or near to proven well to ascertain the limits of the reservoir.

STICKINGJamming of the drill string in the well borehole caused by usually a high differential pressure and a build-up of mud solids on the rock face.

STRADDLE PACKERA rubber packer or seal isolating a section of a well for production testing of the formation in question.

STRATIGRAPHIC TRAP Subsurface formation created by sedimentation that might trap an accumulation of oil and/or gas.

STRINGSee Joint, Drill-string, Casing, etc. Any number of connected joints of tubulars run in the well.

STRUCTUREA geological formation which, if sealed against leakage, could be a potential structural or stratigraphic trap or hydrocarbons. A man-made load-bearing construction, such as an offshore platform, usually designed by structural engineers.

STUCK PIPEDrill pipe, casing, or tubing that cannot be worked in or out of the hole as desired.

SURFACE CASING First string of casing set in well.

SUSPENDED WELLA well, usually a successful discovery well which is left temporarily sealed or plugged to be re-entered for further testing or for production purposes.

SWABBINGOperation using a swab to bring well fluids to the surface when the well does not flow naturally.